Provided are a new α-conotoxin peptide, and a medical composition and a purpose thereof. Further provided are a propeptide, a nucleic acid construct, an expression vector, a transformed cell and a fusion protein of the conotoxin peptide. Disclosed are a method for blocking an acetylcholine receptor and a pharmaceutical purpose of the conotoxin peptide. The α-conotoxin peptide can distinctively block the acetylcholine receptor (nAChRs, such as α3β2 nAChRs, α6/α3β2β3 nAChR, or α3β4 nAChR, or α6/α3β4 nAChR), has activity in treating diseases such as neuralgia, addiction, parkinsonism, dementia, schizophrenia, and cancers, and can be used to prepare medicine such as medicine for analgesia, smoking cessation, and drug treatment, medicine related to mental diseases and cancer treatment, and neuroscience tool medicine.